U.S. patent application number 11/041601 was filed with the patent office on 2006-03-16 for real-time x-ray scanner and remote crawler apparatus and method.
This patent application is currently assigned to The Boeing Company. Invention is credited to Richard H. Bossi, Michael D. Fogarty, Gary E. Georgeson, Morteza Safai.
Application Number | 20060055400 11/041601 |
Document ID | / |
Family ID | 36033217 |
Filed Date | 2006-03-16 |
United States Patent
Application |
20060055400 |
Kind Code |
A1 |
Safai; Morteza ; et
al. |
March 16, 2006 |
Real-time X-ray scanner and remote crawler apparatus and method
Abstract
For inspecting a structure with non-destructive x-ray
inspection, probes are magnetically coupled to opposing surfaces of
the structure. An inspection device may be autonomous with a
feedback-controlled motor and/or a positional encoder. An
inspection device may include wireless operation for at least one
probe. A display may be included to provide real-time visual images
from an x-ray detector or an optical imager.
Inventors: |
Safai; Morteza; (Seattle,
WA) ; Georgeson; Gary E.; (Federal Way, WA) ;
Fogarty; Michael D.; (Auburn, WA) ; Bossi; Richard
H.; (Renton, WA) |
Correspondence
Address: |
ALSTON & BIRD LLP;BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
The Boeing Company
|
Family ID: |
36033217 |
Appl. No.: |
11/041601 |
Filed: |
January 24, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10943088 |
Sep 16, 2004 |
|
|
|
11041601 |
Jan 24, 2005 |
|
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|
Current U.S.
Class: |
324/232 |
Current CPC
Class: |
G01N 23/04 20130101 |
Class at
Publication: |
324/232 |
International
Class: |
G01N 27/72 20060101
G01N027/72 |
Claims
1. A non-destructive inspection apparatus for inspecting a
structure, comprising: a first probe configured for traveling over
a first surface of the structure under inspection, the first probe
comprising: at least one magnetic coupling device; and at least one
x-ray source for emitting radiation for inspecting the structure as
the first probe is moved over the first surface of the structure;
and a second probe configured for traveling over a second surface
of the structure for through transmission inspection, the second
probe comprising: at least one magnetic coupling device for
magnetically coupling the second probe with the first probe,
wherein the magnetic attraction of the magnetic coupling draws the
first and second probes toward the first and second surfaces of the
structure, respectively, and wherein the first and second probes
cooperate by the magnetic coupling to move in a leader-follower
format; and at least one x-ray detector for receiving the
radiation.
2. The apparatus of claim 1, wherein at least one probe further
comprises a motor for moving the probe.
3. The apparatus of claim 1, wherein the magnetic coupling devices
of the first and second probes are selected from the group
consisting of a magnet and a ferromagnetic material insert.
4. The apparatus of claim 1, further comprising a display
communicably coupled to the x-ray detector for presenting x-ray
inspection images captured by the x-ray detector.
5. The apparatus of claim 1, wherein the x-ray detector comprises a
wireless transmitter for transmitting x-ray inspection data.
6. The apparatus of claim 1, wherein the first probe carries an
array of x-ray sources and the second probe carries an array of
x-ray detectors.
7. A probe for inspecting a structure comprising: a housing
configured for traveling over a first surface of the structure
under inspection; at least one x-ray inspection sensor carried by
the housing for inspecting the structure when the probe is moved;
and at least one magnetic coupling device carried by the
housing.
8. The probe of claim 7, wherein the x-ray inspection sensor is an
x-ray source or an x-ray detector.
9. The probe of claim 7, wherein the x-ray inspection sensor is a
microfocus x-ray tube or a CMOS x-ray detector.
10. The probe of claim 7, further comprising a wireless transmitter
communicably coupled to the x-ray inspection sensor.
11. The probe of claim 7, wherein said x-ray inspection sensor is
an x-ray detector, and said x-ray detector is communicably coupled
to a display for imaging inspection data.
12. The probe of claim 7, further comprising a visual inspection
sensor carried by the housing, wherein said x-ray inspection sensor
is a positional encoder, an optical encoder, a linear encoder, a
camera, a directional sensor, or wheel encoder that is communicably
coupled to a display.
13. The probe of claim 7, wherein the probe further comprises a
motor device for moving the probe over the surface.
14. The probe of claim 7, wherein at least one of the magnetic
coupling device comprises is a ring magnet and the x-ray inspection
sensor is disposed within the ring magnet.
15. The probe of claim 7, wherein the probe further comprises at
least one contact member connected to the housing and for
contacting the surface, the contact member being selected from the
group consisting of a wheel, a ball bearing, a fluid bearing, a
skid, a tread, and a combination thereof.
16. A method of inspecting a structure comprising: supporting a
first probe on a first surface of the structure and a second probe
on an opposed second surface of the structure; establishing
magnetic attraction between the first and second probes sufficient
for holding the probes on the first and second surfaces,
respectively; moving one probe, wherein magnetic coupling between
the probes causes the other probe to be correspondingly moved along
the opposing surface of the structure; and transmitting x-ray
inspection signals from an x-ray source carried by one probe into
the structure and receiving signals through the structure by an
x-ray detector carried by the other probe while the probes are
moved along the structure.
17. The method of claim 16, further comprising the step of
displaying x-ray inspection data.
18. The method of claim 16, further comprising the step of
wirelessly transmitting x-ray inspection data from the
detector.
19. The method of claim 18, further comprising the steps of
receiving the transmitted data and displaying the received
data.
20. The method of claim 16, further comprising the step of
adjusting the incident angle of the inspection signals with respect
to the first surface of the structure, and, optionally, adjusting
the angle of the x-ray detector corresponding to the adjustment of
the incident angle of the inspection signals.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of co-pending
application Ser. No. 10/943,088, entitled "Magnetically Attracted
Inspecting Apparatus and Method Using a Ball Bearing," filed Sep.
16, 2004. The contents of U.S. Pat. No. 6,722,202 and co-pending
application Ser. No. 10/752,890, entitled "Non-Destructive
Inspection Device for Inspection Limited-Access Features of a
Structure," filed Jan. 7, 2004; application Ser. No. 10/943,170,
entitled "Alignment Compensator for Magnetically Attracted
Inspecting Apparatus and Method," filed Sep. 16, 2004; and
Application 10/______, entitled "Non-Destructive Stringer
Inspection Apparatus and Method," filed January ______, 2005, are
incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to an apparatus and
method for inspecting a structure and, more particularly, to an
apparatus and method for non-destructive x-ray inspection of a
structure.
BACKGROUND
[0003] Non-destructive inspection (NDI) of structures involves
thoroughly examining a structure without harming the structure or
requiring its significant disassembly. Non-destructive inspection
is typically preferred to avoid the schedule, labor, and costs
associated with removal of a part for inspection, as well as
avoidance of the potential for damaging the structure.
Non-destructive inspection is advantageous for many applications in
which a thorough inspection of the exterior and/or interior of a
structure is required. For example, non-destructive inspection is
commonly used in the aircraft industry to inspect aircraft
structures for any type of internal or external damage to or flaws
in the structure. Inspection may be performed during manufacturing
of a structure and/or after a structure has been put into service.
For example, inspection may be required to validate the integrity
and fitness of a structure for continued use in manufacturing and
future ongoing use in-service. However, access to interior surfaces
is often more difficult or impossible without disassembly, such as
removing a part for inspection from an aircraft.
[0004] Among the structures that are routinely non-destructively
tested are composite structures, such as composite sandwich
structures and other adhesive bonded panels and assemblies. A shift
toward bonded materials dictates that devices and processes are
available to ensure structural integrity, production quality, and
life-cycle support for safe and reliable usage of bonded materials.
In this regard, composite structures are commonly used throughout
the aircraft industry because of the engineering qualities, design
flexibility and low weight, such as the stiffness-to-weight ratio.
As such, it is frequently desirable to inspect composite structures
to identify any flaws, such as cracks, voids or porosity, which
could adversely affect the performance of the composite structure.
For example, typical flaws in composite sandwich structures,
generally made of one or more layers of lightweight honeycomb or
foam core material with composite or metal skins bonded to each
side of the core, include disbonds which occur at the interfaces
between the core and the skin or between the core and a septum
intermediate skin.
[0005] Various types of sensors may be used to perform
non-destructive inspection. One or more sensors may move over the
portion of the structure to be examined, and receive data regarding
the structure. For example, a pulse-echo (PE), through transmission
(TT), or shear wave sensor may be used to obtain ultrasonic data,
such as for thickness gauging, detection of laminar defects and
porosity, and/or crack detection in the structure. Resonance, pulse
echo or mechanical impedance sensors may be used to provide
indications of voids or porosity, such as in adhesive bondlines of
the structure. High resolution inspection of aircraft structure is
commonly performed using semi-automated ultrasonic testing (UT) to
provide a plan view image of the part or structure under
inspection. While solid laminates may be inspected using one-sided
pulse echo ultrasonic (PEU) testing, composite sandwich structures
typically require through-transmission ultrasonic (TTU) testing for
high resolution inspection. In through-transmission ultrasonic
inspection, ultrasonic sensors such as transducers, or a transducer
and a receiver sensor, are positioned facing the other but
contacting opposite sides of the structure. An ultrasonic signal is
transmitted by at least one of the transducers, propagated through
the structure, and received by the other transducer. Data acquired
by sensors, such as TTU transducers, is typically processed by a
processing element, and the processed data may be presented to a
user via a display. To increase the rate or speed at which the
inspection of a structure is conducted, a scanning system may
include arrays of inspection sensors, i.e., arrays of source
transmitters and detectors or receivers. As such, the inspection of
the structure can proceed more rapidly and efficiently, thereby
reducing the costs associated with the inspection.
[0006] Many structures are difficult to accurately inspect using PE
or TTU scanning. X-ray inspection may be preferred for certain
situations because of the high flaw resolution and ability to image
flaws that are not parallel to the surface and without the use of a
couplant. X-ray inspection could be used for close-out inspection
of bonded wings, spar e-beams, and complex composite sandwich
structures. X-ray inspection systems expose film that can be
analyzed. Recently, CCD (charge coupled device) and CMOS
(complementary metal oxide semiconductor) detectors have been used
for the imaging, rather than film.
[0007] Non-destructive inspection may be performed manually by
technicians who typically move an appropriate sensor over the
structure. Manual scanning requires a trained technician to move
the sensor over all portions of the structure needing inspection.
However, typical x-ray inspection applications operate with high
power emissions which prevent manual NDI x-ray inspection.
[0008] Semi-automated inspection systems have been developed to
overcome some of the shortcomings with manual inspection
techniques. For example, the Mobile Automated Scanner (MAUS.RTM.)
system is a mobile scanning system that generally employs a fixed
frame and one or more automated scanning heads typically adapted
for ultrasonic inspection. A MAUS system may be used with
pulse-echo, shear wave, and through-transmission sensors. The fixed
frame may be attached to a surface of a structure to be inspected
by vacuum suction cups, magnets, or like affixation methods.
Smaller MAUS systems may be portable units manually moved over the
surface of a structure by a technician. However, for
through-transmission ultrasonic inspection and x-ray inspection, a
semi-automated inspection system requires access to both sides or
surfaces of a structure which, at least in some circumstances, will
be problematic, if not impossible, particularly for semi-automated
systems that use a fixed frame for control of automated scan
heads.
[0009] Automated inspection systems have also been developed to
overcome the myriad of shortcomings with manual inspection
techniques. For example, the Automated Ultrasonic Scanning System
(AUSS.RTM.) system is a complex mechanical scanning system that
employs through-transmission ultrasonic inspection. The AUSS system
can also perform pulse echo inspections, and simultaneous dual
frequency inspections. The AUSS system has robotically controlled
probe arms that must be positioned proximate the opposed surfaces
of the structure undergoing inspection with one probe arm moving an
ultrasonic transmitter along one surface of the structure, and the
other probe arm correspondingly moving an ultrasonic receiver along
the opposed surface of the structure. Another example robotic
system is the x-ray inspection system used at the William-Gateway
Structural Repair Facility in Mesa, Ariz., for inspection of F-18
tail sections. Conventional automated scanning systems, such as the
AUSS-X system and the William-Gateway x-ray system, therefore
require access to both sides or surfaces of a structure which, at
least in some circumstances, will be problematic, if not
impossible, particularly for very large or small structures. To
maintain the transmitter and receiver in proper alignment and
spacing with one another and with the structure undergoing
inspection, the AUSS-X system has a complex positioning system that
provides motion control in ten axes.
[0010] Access to the structure to conduct inspection may be so
limited that manual or automated inspection is not possible.
Furthermore, scanning systems inspect limited areas up to a few
meters square.
[0011] Conventional x-ray inspection systems are gantry systems.
Many parts, however, are too large; the system cannot reach the
full extent of the part because the scan envelope of the system is
limited.
SUMMARY OF THE INVENTION
[0012] The present invention provides an improved apparatus and
method for inspecting a structure and is the x-ray counterpart of
the ultrasound system described in application Ser. No. 10/943,088.
Embodiments of the present invention combine x-ray inspection
technologies with magnetically coupled inspection probe
technologies to provide x-ray inspection devices that are portable,
can be used for various applications, and provide inspection
results in real-time. Such devices can be used for high resolution
flaw detection in structures of varying shapes and sizes, including
metal and composite structures such as bondlines, weldlines, and
lap joints. Embodiments of apparatus and methods of the present
invention can be used for inspection of structures during
manufacture or in-service. Accordingly, embodiments of the present
invention can replace or reduce the need for conventional
inspection techniques, including film-based x-ray inspection
techniques and large, expensive fixed inspection robots and
gantries, thereby reducing the cost of structural integrity
inspection. Further, embodiments of the present invention provide
new inspection capabilities for x-ray inspection of large and small
structures, structures with limited-access features, and complex
features of structures.
[0013] Apparatus and methods of the present invention use
magnetically coupled probes including respective sensing elements,
such as an x-ray source and an x-ray detector, that are disposed
proximate opposed surfaces of a structure. Additionally, methods
and apparatus of the present invention are capable of operating in
array modes, thereby increasing inspection speed and efficiency
while reducing cost.
[0014] For continuous scanning applications, only one of the probes
need be driven due to the magnetic coupling between the probes.
Thus, methods and apparatus of the present invention are
advantageously adapted to inspect structures in which one surface
of the structure is relatively inaccessible or structures which are
exceptionally large. Further, embodiments of methods and apparatus
of the present invention permit the probes to contact and ride
along the respective surfaces of the structure, thereby reducing or
eliminating the necessary sophistication of a motion control system
that is typically required by conventional scanning systems to
maintain the probes in a predefined orientation with respect to
each other and at a predefined spacing from the respective surface
of a structure undergoing inspection. Permitting the probes to
contact and ride along the respective surfaces of the structure
also may maintain alignment between the probes and/or the x-ray
sensors of the probes. Contact with the surface also permits
accurate position measurement of the inspection device during
continuous scanning, such as keeping an optical or positional
encoder in physical and/or visual contact with the surface of the
structure under inspection.
[0015] Embodiments of the present invention also provide for
wireless inspection operation. By wirelessly transmitting
inspection data, such as digital images from x-ray detectors, a
probe can operate on battery power without any wired connections
for power or data transmission.
[0016] A non-destructive inspection apparatus of the present
invention for inspecting a structure includes two probes which are
configured for traveling over separate surfaces of the structure.
Each probe includes at least one magnetic coupling device for
magnetically coupling the probe with the other such that the
magnetic attraction of the magnetic coupling draws one probe toward
a surface of the structure. The magnetic coupling between the
probes causes movement of both probes when only one probe is
driven. One probe includes an x-ray source for inspecting the
structure as the probe is moved over a surface of the structure.
The other probe includes at least one x-ray detector for
cooperating with the x-ray source. The magnetic coupling devices of
the probes may be magnets configured to provide magnetic attraction
between the probes or a magnet and a ferromagnetic material insert
to provide the magnetic attraction between the probes. One of the
probes may include a display communicably coupled to the x-ray
detector for presenting x-ray inspection images captured by the
x-ray detector. A probe may also include a wireless transmitter
communicably coupled to the x-ray detector for transmitting x-ray
inspection data captured by the x-ray detector.
[0017] A probe of the present invention for inspecting a structure
includes a housing, at least one x-ray inspection sensor, and at
least one magnetic coupling device. The housing is configured for
traveling over a first surface of the structure under inspection.
The housing carries the x-ray inspection sensor and the magnetic
coupling device. The x-ray inspection sensor may be an x-ray
source, an x-ray detector, a microfocus x-ray tube, or a CMOS x-ray
detector. The probe may include a wireless transmitter communicably
coupled to the x-ray inspection sensor. The housing may also carry
a display for imaging x-ray inspection data. The probe may include
an array of x-ray inspection sensors. The probe may include a motor
connected to the housing for moving the probe over the first
surface of the structure for inspection of the structure by the
x-ray inspection sensor. The probe includes at least one magnetic
coupling device for magnetically coupling the probe with another
probe such that the magnetic attraction of the magnetic coupling
draws the probes towards opposing surfaces of the structure. A
magnetic coupling device may be a magnet, such as a permanent
magnet or an electromagnet, or a ferromagnetic material insert. A
magnetic coupling device may be a ring magnet within which the
x-ray inspection sensor may be disposed. The probe may include
contact members for contacting the respective surfaces of the
structure, such as wheels, ball bearings, fluid bearings, skids,
and treads.
[0018] A method of the present invention of inspecting the
structure includes the steps of supporting a first probe on a first
surface of the structure, supporting a second probe on an opposed
second surface of the structure, establishing magnetic attraction
between the first and second probes, moving one of the first and
second probes along the first or second surface of the structure
respectively, and transmitting x-ray inspection signals from an
x-ray source into the structure and receiving x-ray inspection
signals from the structure by an x-ray detector.
[0019] A method of the present invention may include displaying
x-ray inspection data at one probe after receiving x-ray inspection
signals from the structure. Another embodiment includes wirelessly
transmitting x-ray inspection data from at least one probe after
receiving x-ray inspection signals. Another method of present
invention may include adjusting the incident angle of the x-ray
inspection signals of the x-ray source.
BRIEF DESCRIPTION OF THE DRAWING(S)
[0020] FIG. 1 is a schematic diagram of an inspection
apparatus.
[0021] FIG. 2 is a schematic diagram of another inspection
apparatus inspecting a pi-joint bond.
[0022] FIG. 3 is a schematic diagram of yet another inspection
apparatus.
[0023] FIG. 4 is a schematic diagram of yet another inspection
apparatus.
[0024] FIG. 5 is a schematic diagram of an inspection probe.
DETAILED DESCRIPTION
[0025] The present invention will be described more fully with
reference to the accompanying drawings. Some, but not all,
embodiments of the invention are shown. The invention may be
embodied in many different forms and should not be construed as
limited to the described embodiments. Like numbers and variables
refer to like elements and parameters throughout the drawings.
[0026] Embodiments of the present invention can accomplish
versatile high resolution x-ray inspection systems by integrating
an x-ray source, such as a microfocus x-ray tube, with an x-ray
detector, such as a complementary metal oxide semiconductor (CMOS)
detector, using magnetically coupled devices. The microfocus x-ray
source, or tube, may be attached to one of the magnetically coupled
devices and a real-time x-ray detector, such as a CMOS detector,
may be attached to the magnetically coupled device on the opposite
side of the structure under inspection. This configuration allows
for real-time inspection with simple alignment of the x-ray source
and detector using the magnetic coupling between the devices on
opposing sides of the structure. Further, the magnetic coupling of
the devices on opposing sides of the surface allows for moving the
inspection apparatus along the structure for inspection of large
and complex composite, metal, and ceramic structures.
[0027] An advantage of using a microfocus x-ray source is that a
microfocus x-ray source, or tube, can produce less than one
micrometer (.mu.m) diameter focal spot size along the axis of the
x-ray beam at approximately 162 kilovolts (kV) energy with an x-ray
tube current of 200 microamps (.mu.A). The functional capabilities
of microfocus x-ray tubes allow for high resolution, nondestructive
inspection of structures, including structures which would
otherwise be too thick for conventional inspection using pulse echo
or through transmission ultrasonic inspection. In addition,
microfocus x-ray sources generate less scattered ionizing radiation
than conventional x-ray sources. Further, the use of a microfocus
x-ray tube realizes a low-dose x-ray inspection technology that
reduces the safety issues related to conventional radiographic
inspection. For example, many composite structures can be inspected
with x-ray beams with as low as 20 kiloelectronvolts (KeV) energy
values. Using such equipment reduces shielding problems and allows
operators to be in the area of the inspection operation.
[0028] Real time high resolution x-ray detectors, such as a CMOS
detector, may be used in conjunction with an x-ray source, such as
a CsI, Gd.sub.2O.sub.2S or CaWO.sub.4 x-ray scintillator, for high
resolution detecting capability. The use of CMOS detectors have
several advantages, including relatively low cost, high resolution
imaging capabilities because of small pixel size, and antiblooming
capability, meaning that adjacent detectors will not saturate with
intense illumination which occurs in CCD type detectors. Further,
the amplification circuit and all necessary logic circuits and
multiplexing may be integrated onto the CMOS detector chip to allow
for high speed data transfer, shuttering, windowing, and
asynchronizing of the CMOS detector. Although CMOS detectors may be
preferred in many applications, an x-ray detector of the present
invention can also be a CCD detector, amorphous selenium, amorphous
silicon, or other silicon-based or solid-state linear or array
detector. More generally, these detectors may be used without x-ray
sensitive scintillators. Further, x-ray detectors may be connected
to or include digital microprocessors and/or image processors with
auto defect recognition.
[0029] Inspection devices can inspect a variety of structures
formed of various materials. For inspection devices which transmit
magnetic fields through the structure, however, the structure is
preferably non-magnetic, that is, the structure preferably has no
magnetic permeability. Structures that may be inspected with an
embodiment of an inspection device of the present invention may
include, but are not limited to, composites such as carbon fiber or
graphite reinforced epoxy (Gr/Ep), non-ferromagnetic metals (e.g.
aluminum alloy, titanium alloy, or aluminum or titanium hybrid
laminates such as GLARE or Ti/Gr), and polymers. The surfaces and
intermediate surfaces commonly referred to as septums, which
collectively define the test article are non-magnetic to allow
magnetic coupling between the probes. For example, the structure 4
in FIG. 1 is a septumized core material and the structure 104 in
FIG. 2 is a bonded composite pi-joint weld.
[0030] While a portion of a relatively simple structure is depicted
in FIG. 1, a structure being inspected may be any myriad of shapes
and/or sizes and used in a variety of applications, including
aircraft, marine vehicles, automobiles, spacecraft and the like, as
well as buildings. Moreover, the structure may be inspected prior
to assembly or following assembly, as desired.
[0031] Components for an x-ray scanner such as an x-ray source and
an x-ray detector, may be supported on opposing surfaces of the
structure and may include magnetically coupled probes, as described
in co-pending application Ser. Nos. 10/943,088; 10/752,890; or
10/943,170. Using magnetically coupled probes aligns the x-ray
source and x-ray detector as required for the inspection. For
example, a weldline may be inspected at 45.degree. angle relative
to the skin of the structure in which case the x-ray source, and
possibly also the x-ray detector, could be oriented at an angle of
45.degree. with respect to the skin. In such off-axis
(non-perpendicular) orientation applications, the x-ray source and
x-ray detector may not be aligned across from each other, but at
corresponding positions such that the focus of the x-ray signals
are transmitted from the x-ray source through the structure to the
x-ray detector. In an embodiment of the present invention for such
an application, the x-ray source, and possibly the x-ray detector,
can be adjusted or set at a specific angle using a pivot point on
the magnetically coupled probe. The specific angle for the x-ray
source, and possibly x-ray detector, may be motor-controlled or
manually adjusted.
[0032] Embodiments of the present invention may include wireless
operation, such as wireless transmission of the digital x-ray
images captured by the x-ray detector. Accordingly, at least one of
the magnetically coupled probes, typically the probe supporting the
x-ray detector, can be used without having to feed wires into the
structure for transmission of the digital images, and possibly also
for powering the device. In many situations, the wireless
operation, and cordless capability, of an inspection probe may be
advantageous, such as in a situation where the magnetically coupled
probe and x-ray detector are used in limited access areas, such as
inside a hat stringer or along the inside of an internal bondline.
To provide a completely wireless inspection probe, battery power
may be used for any type of equipment which requires power, such as
the x-ray detector and a wireless transmitter. A wireless
transmitter be any type of technology which permits transmission of
the digital x-ray images captured by the x-ray detector, such as a
cellular technology, Bluetooth wireless transmission, or light
means for wireless transmission of data. Wireless operation can
also be provided where other elements of a probe are generated by
battery power, such as operating a battery-powered x-ray source
with a wireless controller. In addition, an optical imager may be
used to provide visual identification of the internal position or
feature of the structure under inspection to assist in the
interpretation and/or location of the x-ray inspection probe on an
opposing surface of the part. For example, an inspection probe
located on the outside of a complex structure under inspection can
include, in addition to the x-ray source, a display for displaying
digital images captured by the x-ray detector or an optical imager
of the magnetically coupled probe on the opposing surface of the
structure. Permitting the technician to immediately view in real
time the images captured by an x-ray detector or an optical imager
of a magnetically coupled probe on the opposing surface of the
structure may improve the inspection of the structure, such as by
providing the technician the ability to interpret the location of
the magnetically coupled probe and the images captured thereby.
[0033] FIG. 1 is a schematic diagram of an inspection apparatus of
the present invention. The inspection apparatus 2 is shown
inspecting a septumized core material 4 and a first probe 6
disposed proximate a first surface 4a of the structure 4 and a
second probe 8 disposed proximate an opposed second surface 4b of
the structure. Suitable probes are described in U.S. Pat. No.
6,722,202 and co-pending application Ser. Nos. 10/943,088;
10/752,890; 10/943,170; 10/943,135; and 10/______, entitled
"Non-Destructive Stringer Inspection Apparatus and Method," filed
January ______, 2005. The shape and size of an inspection probe,
and its housing may be any shape or size capable of operating in
accordance with the present invention. One probe is disposed in
contact with one surface of the structure. The probes are initially
operably aligned as shown in FIG. 1. The alignment is maintained as
the probes are moved along the respective surfaces of the structure
for inspection.
[0034] Each probe 6, 8 includes a magnetic coupling device 30
supported by the probes 6, 8, such as disposed within a housing of
each probe. The magnetic coupling devices 30 magnetically attract
the first and second probes 6, 8 toward the respective surfaces of
the structure 4. Magnetic coupling devices, such as magnets and/or
ferromagnetic material inserts, may also be used to provide
alignment between the first and second probes 6, 8, more
particularly the inspection sensors thereof such as a microfocus
low dose x-ray source 10 of the first probe 6 and a digital imager
x-ray detector 12 of the second probe 8. Magnetic coupling may be
adjusted by changing the size and/or strength of a magnet, such as
a permanent magnet, or the strength of an electromagnet. For
example, to decrease friction control, electromagnetic strength may
be decreased, but to increase the holding support of the magnetic
coupling such as when using an inspection device in an inverted
position, electromagnetic strength may be increased.
[0035] The probes 6, 8 include inspection sensors for inspecting
the structure 4 as the probes 6, 8 are moved. The inspection
sensors may be, for example, optical imaging devices or x-ray
sensors. Advantageously, the probes include x-ray sensors which
cooperate to provide low-dose, high resolution digital imaging of
the structure under inspection. For example, a first probe 6
includes a microfocus x-ray source tube 10, and the second probe 8
includes a digital imaging x-ray detector 12. A second probe 8 may
also include an optical sensor such as a camera 42 which is used to
provide visual images of a surface 4b to aid in the inspection of
the structure 4 by providing visual information about the location
of the second probe 8 on the second surface 4b of the structure 4.
The first probe 6 preferably includes a radiation shield 14 to
contain the x-ray emissions from the microfocus x-ray source
10.
[0036] At least one probe may also include an x-ray detector, a
wireless transmitter 40, or a battery 44. The wireless transmitter
40 is communicably coupled to the x-ray detector 12 of the second
probe 8, and possibly other inspection sensors such as a camera 42.
The battery 44 is used to power elements of a probe which require
an external power source. By using a wireless transmitter 40 and a
battery 44, a probe 8 is capable of functioning completely free of
any wires or physical connections. Accordingly, the probe 8 is
capable of operating to inspect a limited access structure such as
being positioned and moving within an enclosed structure with
limited access to insert the probe 8 or being positioned and moving
along a limited access structure such as a bond line. At least one
probe includes the x-ray source 10 and a display 20 for displaying
the x-ray images captured by the x-ray detector 12 and/or images
captured by other sensors such as a camera 42. By including a
display 20 a technician can analyze the inspection data and/or
positional information in real time during the inspection of the
structure 4. A display may be co-located with a probe of an
apparatus as in FIG. 1 or communicably connected to an x-ray
detector and remotely located. To maintain consistency throughout
this application, the probe which includes the x-ray source is
referred to as the first probe and the probe which includes the
x-ray detector is referred to as the second probe.
[0037] Embodiments of the present invention may be scaled and
adapted to be driven by an automated system, such as an AUSS
system, or used as a manual inspection tool. For example, a yoke
attachment may be attached to a magnetically attracted scanning
probe and also connected to a scanning bridge of an automated
system.
[0038] To conduct non-destructive x-ray inspection, the probes are
disposed proximate to and generally in contact with opposed
surfaces 4a, 4b of a structure 4 while maintaining alignment and
magnetic attraction. Contact members, such as wheels, ball
bearings, fluid bearings, skids, or treads, may be used to maintain
adequate spacing between the probe and the surface of the part
under inspection. In such a manner, the contact members may be used
to prevent the probe from contacting and possibly damaging the
surface of the part. Further, the contact members provide the probe
the ability to translate along the surface of the part for
continuous scanning, and to reduce the frictional drag of the probe
on the surface of the structure being inspected to permit smooth
translation of the probe across the surface. As such, the
orientation and spacing of the probe relative to the surface of the
structure may be maintained by the contact members without
requiring complex motion control systems. Independence from motion
control systems reduces the cost of inspection and permits
inspection where a robotic arm or other conventional motion control
system would have difficulty positioning the sensors.
[0039] The inspection sensors are activated to inspect the
structure. Although not shown, a drive element, such as a battery
or other power source, is generally associated with the inspection
sensor of the first probe so as to actuate the inspection sensors
which transmit x-ray signals through the structure for detection by
detectors on an opposing side of the structure.
[0040] While transmitting x-ray signals, the probes 6, 8 are moved
along the surfaces 4a, 4b. While the motive force required to move
the probes along the respective surfaces of the structure may be
applied in various manners, typically at least one probe includes a
drive motor, such as a smart stepper motor. Magnetic attraction
between the probes 6, 8 and, more particularly, between the
magnetic coupling devices 30, causes the non-driven probe, also
referred to as a follower, keeper, holder, or tracking probe, moves
in correspondence with the driven probe. The tracking probe moves
to remain in an aligned, opposed position relative to a driven
probe as the driven probe is moved along a first surface of a
structure under inspection even with the tracking probe riding on
the interior of a cylindrical structure or other structure having a
closed shape.
[0041] Signals received by the detector(s) of a probe 8 can be
stored along with an indication of the time or position at which
the x-ray signals are received. Accordingly, each probe 6, 8 may
included an encoder, such as an optical encoder, a linear encoder,
an optical sensor, an optical imager or camera, a directional
sensor, or wheel encoder to provide feedback of the position,
speed, direction, and/or velocity of the probe. For example,
embodiments of the present invention may use a smart stepper motor
and an optical encoder to accurately position and move the probes
for inspection. The ultrasonic signals may be stored by a memory
device electrically connected with the probe 8. By analyzing the
x-ray signals received by the detector(s), the integrity of the
structure 4 as well as any flaws can be determined.
[0042] FIG. 2 is a schematic diagram of yet another inspection
apparatus of the present invention. The inspection apparatus 102 is
shown inspecting a bonded composite pi-joint. Due to the particular
shape of the PI-joint, the x-ray source 10 of the first inspection
probe 106 is oriented at an angle relative to the first surface
104a of the structure 104 under inspection. The x-ray detector 12
of the second probe 108 is oriented at a corresponding angle to the
second surface 104b of the structure 104 corresponding to the
incident angle of the x-ray source 10. The x-ray source 10 and
x-ray detector 12 may be fixed at these corresponding angles of
orientation with respect to the respective surfaces of the
structure under inspection. Alternatively, an embodiment of the
present invention may include mechanics which permit the angle of
the x-ray source 10 and the x-ray detector 12 to be adjusted to any
specific angle, such as using rotational mechanics supported by the
magnetically coupled probes to re-orient the incident angles of the
x-ray source and x-ray detector. A motor may be used to control the
specific incident angles for the x-ray source and x-ray detector.
In such a manner, an inspection apparatus may be electronically
controlled by a motion controller such as a general purpose
computer including computer program software instructions to
operate the motors for the rotational mechanics to control the
incident angles of the x-ray source and x-ray detector.
[0043] In FIG. 3, the inspection apparatus 200 includes
magnetically coupled inspection probes 206, 208 that may be
configured to house magnetically attracted ring magnets to provide
corresponding orientation between the magnetically coupled probes
and inspection sensors. For example, the first probe 206 may
include a microfocus x-ray tube 10 disposed within the center of a
ring magnet. Similarly, the second probe 208 may include an x-ray
detector, such as a CMOS detector 212 and fluorescent screen 213
disposed within the center of a ring magnet. The inspection
apparatus 200 may also include a computer image processor 204
located proximate to or separate from the second probe 208. The
computer image processor 240 may be used to analyze the digital
images captured by the CMOS detector 212 to produce a visual image
made available to a technician to analyze the condition of the
structure 204 under inspection, such as to identify a defect 201
within the structure 204. Pattern recognition may also be
automated.
[0044] In FIG. 4, the inspection apparatus 302 includes a
quasi-linear array of microfocus x-ray sources 310 and
corresponding x-ray detectors 312. The array of x-ray sources 310
and x-ray detectors 312 allow scanning larger areas rapidly. The
multiple images produced by the array of x-ray detectors 312 can be
digitally combined to produce a single inspection image.
[0045] In FIG. 5, the inspection probe 402 includes an x-ray source
410 surrounded by ceramic radiation shielding 414. The ceramic
radiation shielding includes an exit window 410 which permits the
transmission of x-ray inspection signals from the x-ray source 410.
The inspection probe 402 includes a drive motor 450, such as a
smart stepper motor, which provides translational mechanics for the
motion of the probe 402 along the surface of a structure under
inspection. For example, the probe includes contact members 466,
such as tracked wheels, i.e., wheels which rotate a tread.
[0046] For non-destructive x-ray inspection, probes are
magnetically coupled to opposing surfaces of the structure under
inspection. An inspection device may be autonomous with a
feedback-controlled motor and/or a positional encoder. An
inspection device may include wireless operation for at least one
probe. A display may be included to assist in the inspection of a
structure by providing real-time visual images from an x-ray
detector or an optical imager.
[0047] The invention should not be limited to the specific
disclosed embodiments. Specific terms are used in a generic and
descriptive sense only and not for purposes of limitation.
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